diff --git a/executor/grant_test.go b/executor/grant_test.go
index 8ccfac3533fb6..df45169b23ff5 100644
--- a/executor/grant_test.go
+++ b/executor/grant_test.go
@@ -366,6 +366,14 @@ func (s *testSuite3) TestMaintainRequire(c *C) {
 	c.Assert(err, NotNil)
 }
 
+func (s *testSuite3) TestMaintainAuthString(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec(`CREATE USER 'maint_auth_str1'@'%' IDENTIFIED BY 'foo'`)
+	tk.MustQuery("SELECT authentication_string FROM mysql.user WHERE `Host` = '%' and `User` = 'maint_auth_str1'").Check(testkit.Rows("*F3A2A51A9B0F2BE2468926B4132313728C250DBF"))
+	tk.MustExec(`ALTER USER 'maint_auth_str1'@'%' REQUIRE SSL`)
+	tk.MustQuery("SELECT authentication_string FROM mysql.user WHERE `Host` = '%' and `User` = 'maint_auth_str1'").Check(testkit.Rows("*F3A2A51A9B0F2BE2468926B4132313728C250DBF"))
+}
+
 func (s *testSuite3) TestGrantOnNonExistTable(c *C) {
 	tk := testkit.NewTestKit(c, s.store)
 	tk.MustExec("create user genius")
diff --git a/executor/simple.go b/executor/simple.go
index 95067f42621d0..3d21e150c2b3b 100644
--- a/executor/simple.go
+++ b/executor/simple.go
@@ -848,10 +848,16 @@ func (e *SimpleExec) executeAlterUser(s *ast.AlterUserStmt) error {
 
 	failedUsers := make([]string, 0, len(s.Specs))
 	for _, spec := range s.Specs {
-		if spec.User.CurrentUser {
-			user := e.ctx.GetSessionVars().User
+		user := e.ctx.GetSessionVars().User
+		if spec.User.CurrentUser || ((user != nil) && (user.Username == spec.User.Username) && (user.AuthHostname == spec.User.Hostname)) {
 			spec.User.Username = user.Username
 			spec.User.Hostname = user.AuthHostname
+		} else {
+			checker := privilege.GetPrivilegeManager(e.ctx)
+			activeRoles := e.ctx.GetSessionVars().ActiveRoles
+			if checker != nil && !checker.RequestVerification(activeRoles, "", "", "", mysql.SuperPriv) {
+				return ErrDBaccessDenied.GenWithStackByArgs(spec.User.Username, spec.User.Hostname, "mysql")
+			}
 		}
 
 		exists, err := userExists(e.ctx, spec.User.Username, spec.User.Hostname)
@@ -863,22 +869,25 @@ func (e *SimpleExec) executeAlterUser(s *ast.AlterUserStmt) error {
 			failedUsers = append(failedUsers, user)
 			continue
 		}
-		pwd, ok := spec.EncodedPassword()
-		if !ok {
-			return errors.Trace(ErrPasswordFormat)
-		}
+
 		exec := e.ctx.(sqlexec.RestrictedSQLExecutor)
-		stmt, err := exec.ParseWithParams(context.TODO(), `UPDATE %n.%n SET authentication_string=%? WHERE Host=%? and User=%?;`, mysql.SystemDB, mysql.UserTable, pwd, spec.User.Hostname, spec.User.Username)
-		if err != nil {
-			return err
-		}
-		_, _, err = exec.ExecRestrictedStmt(context.TODO(), stmt)
-		if err != nil {
-			failedUsers = append(failedUsers, spec.User.String())
+		if spec.AuthOpt != nil {
+			pwd, ok := spec.EncodedPassword()
+			if !ok {
+				return errors.Trace(ErrPasswordFormat)
+			}
+			stmt, err := exec.ParseWithParams(context.TODO(), `UPDATE %n.%n SET authentication_string=%? WHERE Host=%? and User=%?;`, mysql.SystemDB, mysql.UserTable, pwd, spec.User.Hostname, spec.User.Username)
+			if err != nil {
+				return err
+			}
+			_, _, err = exec.ExecRestrictedStmt(context.TODO(), stmt)
+			if err != nil {
+				failedUsers = append(failedUsers, spec.User.String())
+			}
 		}
 
 		if len(privData) > 0 {
-			stmt, err = exec.ParseWithParams(context.TODO(), "INSERT INTO %n.%n (Host, User, Priv) VALUES (%?,%?,%?) ON DUPLICATE KEY UPDATE Priv = values(Priv)", mysql.SystemDB, mysql.GlobalPrivTable, spec.User.Hostname, spec.User.Username, string(hack.String(privData)))
+			stmt, err := exec.ParseWithParams(context.TODO(), "INSERT INTO %n.%n (Host, User, Priv) VALUES (%?,%?,%?) ON DUPLICATE KEY UPDATE Priv = values(Priv)", mysql.SystemDB, mysql.GlobalPrivTable, spec.User.Hostname, spec.User.Username, string(hack.String(privData)))
 			if err != nil {
 				return err
 			}
diff --git a/privilege/privileges/privileges_test.go b/privilege/privileges/privileges_test.go
index 1bb69be14c826..4d0b42a6d37ff 100644
--- a/privilege/privileges/privileges_test.go
+++ b/privilege/privileges/privileges_test.go
@@ -468,6 +468,28 @@ func (s *testPrivilegeSuite) TestSetPasswdStmt(c *C) {
 	c.Assert(err, NotNil)
 }
 
+func (s *testPrivilegeSuite) TestAlterUserStmt(c *C) {
+	se := newSession(c, s.store, s.dbName)
+
+	// high privileged user setting password for other user (passes)
+	mustExec(c, se, "CREATE USER 'superuser2'")
+	mustExec(c, se, "CREATE USER 'nobodyuser2'")
+	mustExec(c, se, "CREATE USER 'nobodyuser3'")
+	mustExec(c, se, "GRANT ALL ON *.* TO 'superuser2'")
+	mustExec(c, se, "GRANT CREATE USER ON *.* TO 'nobodyuser2'")
+
+	c.Assert(se.Auth(&auth.UserIdentity{Username: "superuser2", Hostname: "localhost", AuthUsername: "superuser2", AuthHostname: "%"}, nil, nil), IsTrue)
+	mustExec(c, se, "ALTER USER 'nobodyuser2' IDENTIFIED BY 'newpassword'")
+	mustExec(c, se, "ALTER USER 'nobodyuser2' IDENTIFIED BY ''")
+
+	// low privileged user trying to set password for other user (fails)
+	c.Assert(se.Auth(&auth.UserIdentity{Username: "nobodyuser2", Hostname: "localhost", AuthUsername: "nobodyuser2", AuthHostname: "%"}, nil, nil), IsTrue)
+	mustExec(c, se, "ALTER USER 'nobodyuser2' IDENTIFIED BY 'newpassword'")
+	mustExec(c, se, "ALTER USER 'nobodyuser2' IDENTIFIED BY ''")
+	_, err := se.ExecuteInternal(context.Background(), "ALTER USER 'superuser2' IDENTIFIED BY 'newpassword'")
+	c.Assert(err, NotNil)
+}
+
 func (s *testPrivilegeSuite) TestSelectViewSecurity(c *C) {
 	se := newSession(c, s.store, s.dbName)
 	ctx, _ := se.(sessionctx.Context)